The invention relates to a sealing arrangement and sealing method of a measuring device.
The measuring and controlling of aggressive chemicals by automatic in-line measuring devices and actuators is well justified due to the dangerous nature and high cost of the chemicals. The challenge in the measuring devices of aggressive chemical is the connecting of an optical or other measuring element to the other mechanics and process in a leak-proof manner so that the liquid or gas being measured stays in the measuring vessel or burette and cannot make it inside the measuring device. It is difficult, even impossible, to seal aggressive chemicals, such as fluorhydric acid and sulphuric acid, because when the chemicals gasify their small molecules manage to penetrate the sealant.
In connection with aggressive chemicals, fluorelastomers and perfluoroelastomers are typically used, which withstand aggressive chemicals well without being damaged.
The problem with the arrangement described above is that the sealing materials allow gasses to go through them, which causes damage to the sensitive optical, mechanical, or electronic parts inside the measuring device.